I noticed today too that v66 is now stable. Now I have questions below:
1. You said that MPM_PREFORK and DSO+Mod_RUID2 is not compatible with HTTP2. Is there any reason why cPanel refuse to utilize MPM_WORKER and SuPHP as default ?
I'm wondering because cPanel is the most prevalent control panel in the world. If they will not change the default, HTTP/2 adaptation will be very slow.
2. There's this one hosting company who wrote an article blog a few days ago on how to enable HTTP2 on WHM with EA4 . The article mentioned to install php 7.x and set PHP 7 as default PHP version for all the websites. Well, I have a script that still uses PHP 5.6, does it mean that HTTP/2 does not work on PHP 5, and therefore my PHP5-only compatible scripts will go awry if I enable HTTP/2 on my vps server?
As I can't speak for cPanel, I know we provision cPanel as MPM_PREFORK and DSO+Mod_RUID2; as that's the most optimized setup we can offer for our customers without any foreseeable issues. This allows for most users who do not require additional configuration to setup their websites and go without the need of adjustment.
Most hosting companies, including us, are going to push the recommendation to utilize PHP 7.0. This is what I suspect the company in question had in mind when writing their guide. We all want websites to be ran on the latest platform to ensure security.
That being said, I have HTTP/2 installed on my test environment on several websites and I set PHP 5 and did not experience any errors. Everyone's experience may differ.
Someone feel free to correct me if this is not the case.
However, I would expect to see more issues on HTTP/2 when dealing with older browsers due to the protocol not being supported due to how HTTP/2 is detected.